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Ivyspring International Publisher International Journal of Medical Sciences 2018; 15(3): 223-227. doi: 10.7150/ijms.21748 Research Paper Comparison of Floaters after with Different Viscoelastics Jinsoo Kim, Hak Jun Lee, In Won Park, Soon Il Kwon

Department of Ophthalmology, Hallym University Sacred Heart Hospital, Anyang, Republic of Korea

 Corresponding author: Soon Il Kwon, Hallym University Sacred Heart Hospital, Anyang, Republic of Korea. Zip code: 14068; Phone: 82-10- 9075- 5854; Fax: 82-31-380-3837; Email: [email protected], [email protected]

© Ivyspring International Publisher. This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY-NC) license (https://creativecommons.org/licenses/by-nc/4.0/). See http://ivyspring.com/terms for full terms and conditions.

Received: 2017.07.03; Accepted: 2017.09.01; Published: 2018.01.01

Abstract Purpose: To investigate whether there is a difference between symptoms of floaters according to the type of ophthalmic viscosurgical devices(OVDs) used during . Methods: A total of 112 had undergone standard phacosurgery with the dispersive OVDs(Group1). Group2 comprised 117 eyes that underwent phacosurgery with the dispersive OVDs, but between continuous curvilinear and hydrodissection, some OVDs had been removed. Group3 included 120 eyes that had undergone phacosurgery with the cohesive OVDs. Results: 14 eyes (12.5%) of Group1 had new-onset floater after surgery whereas 6 eyes (5.13%) in Group2, and 7 eyes (5.83%) in Group3 at the day after and a week after surgery. This was significantly higher in Group1 than Group2 and Group3, respectively (p=0.047,0.049). Conclusion: Cataract surgery with dispersive OVD can predispose the to an increased floater symptom. Therefore, surgeons should consider release some OVDs during hydrodissection with dispersive viscoelastics and keep trying to avoid IOP surge during surgery.

Key words: Cataract surgery; Floaters; Ophthalmic viscosurgical devices; Phacoemulsification; Viscoelastics

Introduction The surgical technique of phacoemulsification ophthalmic viscoelastic devices (OVDs) enter the surgical technique has undergone significant vitreous cavity when the PC-anterior hyaloid improvement over the past several decades, and it membrane (AHM) barrier, which is made up of the results in improvement of visual acuity in many zonule of Zinn and the AHM, ruptures [6]. patients with cataract [1,2]. However, although the Hydrodissection is considered the most likely cause of vision improves after phacoemulsification, many an AHM tear. Hydrodissection is the method of patients complain of discomfort. Floaters are one of injecting fluid into the cortical layer of the capsule the most common complaints in the ophthalmic care under the lens to separate the lens nucleus from the setting. Vitreous floaters usually occur with posterior cortex capsule, and is an important step in the vitreous detachment (PVD), and phacoemulsification mobilization of the nucleus [7]. Since the intraocular can increase the risk of PVD. Typically, floaters are a pressure (IOP) becomes highest at this stage during sensation of gray or dark spots moving in the visual phacosurgery, removing some OVDs before the field and may persist for months or years [3-5]. Unlike hydrodissection could reduce the spike in IOP [8,9]. the typical symptoms of floaters, some patients The aim of this study was to investigate whether there complain of tiny floaters that show up a day after is a difference between symptoms of floaters cataract surgery and disappear within a few months. according to the type of OVDs used during cataract This usually happens with posterior capsular (PC) surgery. In addition, we investigated if there is a rupture, but it can also develop in a large number of difference in symptoms of floaters experienced after patients who undergo phacosurgery without surgery when some OVDs are removed during significant surgical complications. Another possible hydrodissection. cause for this phenomenon is that lens particles and

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Methods to 4 based on the number of new-onset floaters as follows: Score 1, no new-onset floater; Score 2, 1 or 2 This retrospective observational study was new-onset floaters; Score 3, more than 2 and less than conducted in accordance with the tenets of the 10 new-onset floaters; Score 4, more than 10 Declaration of Helsinki and was approved by the new-onset floaters. We focused on patients with Institutional Review Board of Hallym University floaters with a score of 4; patients with scores of 1 Sacred Heart Hospital. The medical records of all through 3 were excluded as the new occurrence of a patients who were older than 18 years and underwent few floaters could be the manifestation of preexisting phacoemulsification cataract surgery from March floaters that were not recognized under foggy vision. 2011 to June 2014 at the Hallym University Sacred Standard cataract surgery was performed by a Heart hospital, Korea, were reviewed. Exclusion single surgeon (S.K.). After a 3-mm corneal incision criteria were patients who experienced adverse events was made, the anterior chamber was filled with during phacosurgery such as posterior capsular viscoelastic material (Disco Visc; Alcon). In the OVD rupture, zonular dialysis, or radial tear. Difficult removal group (Group 2), we removed some surgical cases such as brunescent cataract, shallow viscoelastics through the corneal incision site before anterior chamber, zonular dehiscence, etc. were also hydrodissection. Then, hydrodissection was excluded even though the surgery was not eventful. performed slowly and carefully with the use of a Patients with long axial length (>27.0mm) or high 10-ml disposable syringe equipped with a Healon myopia (spherical equivalent > 6.0D), previous ocular needle through a side port. The needle was inserted surgery or trauma, and other ocular conditions which beneath the anterior lens capsule. Next, would be expected to be associated with an increased phacoemulsification was performed on the lens number of floaters, such as retinal tear, nucleus and cortex as follows: The bottle height was rhegmatogenous retinal detachment, diabetic adjusted to 78 cm above eye level, and then, the retinopathy or asteroid hyalosis were excluded too. procedure was performed at a vacuum limit of 220 We enrolled 349 eyes from 319 patients with mmHg and a phacoemulsification power limit of 60%. cataracts, all patients had undergone uneventful After filling up the capsular bag with viscoelastic standard phacoemulsification through a 3-mm material, we used an injector to implant an IOL incision with the implantation of an intraocular lens (Tecnis 1-piece, Abbott medical optics) into the bag. (IOL). A total of 112 eyes that had undergone After IOL implantation, the viscoelastic material was standard phacosurgery with dispersive OVDs thoroughly washed via aspiration at a fixed flow rate (DiscoVisc; Alcon) were assigned to Group 1. Group 2 of 25 ml/min and a maximum linear vacuum power comprised 117 eyes that had also undergone standard of 500 mmHg. In Group 3, standard cataract surgery phacosurgery with dispersive OVDs, but between was performed with cohesive OVDs (Microvisc; continuous curvilinear capsulorhexis (CCC) and BohusBiotech). hydrodissection, some OVDs had been removed The chi-square test was applied for comparisons through the incision site. Group 3 included 120 eyes of initial demographic features such as age, sex, visual that had undergone standard phacosurgery with acuity, and IOP, and incidence of vitreous floater at cohesive OVDs (Microvisc; BohusBiotech); the OVDs follow-up visit between the groups 1, 2, and 3. had deliberately not been removed before Analysis was performed using SPSS ver.12.0 (SPSS hydrodissection. After cataract surgery, all patients Inc., Chicago, IL, USA) and the level of significance underwent follow-up at 1 day, 1 week, 1 month, and 2 was set at p < 0.05. months. At every visit, participants were questioned about floater symptoms, and in case of presence of Results symptoms, how many floaters the participant could recognize, which is routine. Then, patients would The Demographics of the study population are have a non-mydriatic , dilated shown in Table 1. Mean age (Group 1: 67.53 ± 13.55 fundus examination or optical coherence tomography years, Group 2: 68.15 ± 13.24 years, Group 3: 66.89 ± if they were needed. The parameters of this study 13.75 years), sex ratio, and baseline IOP (Group1 : included demographics, preexisting eye diseases and 13.15 ± 3.14 mmHg, Group 2: 13.50 ± 3.03 mmHg, details of cataract surgeries (including complications) Group 3: 13.170 ± 3.23 mmHg) were not significantly undergone. In addition, best corrected visual acuity different between the three groups (Table 1). (BCVA) using the Snellen chart, IOP and the presence All 349 eyes underwent a standard 3-mm of floaters were evaluated. Intraocular pressure was incision phacoemulsification without any significant measured with pneumatic tonometry. complications. A high (30 mmHg or more) was Additionally, we evaluated the degree of floater observed in only 5 eyes (3 eyes in Group 1 and 2 eyes symptoms. Every floater was assigned a score from 1 in Group 2) on the day after surgery, but normalized

http://www.medsci.org Int. J. Med. Sci. 2018, Vol. 15 225 with medication within 1 week in all patients. No Table 2. Comparison of number of patients with new-onset significant difference in postoperative IOP was floater symptom between Group1 and Group 2. observed among the three groups. Although there Patients Group 1 Group 2 p-value† was no statistically significant difference in with POD 1 day 14 (12.5%) 6 (5.13%) 0.047 postoperative IOP between the three groups, new-onset POD 1 week 14 (12.5%) 6 (5.13%) 0.047 floaters POD 1 10 (8.93%) 7 (5.98%) 0.395 new-onset floater symptoms after cataract surgery month were experienced by 14 eyes in Group 1 (12.5%), POD 2 8 (7.14%) 5 (4.27%) 0.348 whereas only 6 eyes (5.13%) in Group 2 and 7 eyes months ≥10 new-onset floaters 6 (5.35%) 0 0.094 (5.83%) in Group 3 experienced such symptoms on the during entire follow-up day after surgery and a week after surgery, †Mann Whitney U- test P< 0.05 respectively, which was statistically different (p = Group 1: used dispersive ophthalmic viscosurgical devices (OVDs) and did not remove them before hydrodissection. Group 2: used dispersive OVDs and removed 0.047 and 0.049, respectively; Figure 1; Table 2, 3). some dispersive OVDs before hydrodissection. Group 3: used cohesive OVDs. Floater symptoms in Group 1 improved with time; POD: postoperative day. therefore, no significant differences existed among three groups at 1 month and 2 months The floater scores show that 6 eyes in Group 1 postoperatively. (5.35%) had more than 10 new floaters (score 4), whereas no eye in Group 2 and 1 eye in Group 3 had severe floater symptoms (Table 2, Table 3). Although Table 1. Demographics of study groups. Group 1 had more severe floater symptoms than

Group 1 Group 2 p-value† Group 3 p-value† Group 2 and 3, statistically significant differences did Number of eyes 112 117 120 not exist in floater scores. Age (years) 67.53 ±13.55 68.15 ± 0.613 66.89± 0.421 13.24 13.75 Table 3. Comparison of number of patients with new-onset Sex (Male : 1 : 0.81 1 : 0.85 0.915 1:0.91 0.724 floater symptom between Group1 and Group 3. Female) IOP (mmHg) Patients Group 1 Group 3 p-value† Baseline 13.15 ± 3.14 13.50 ± 3.03 0.349 13.17 ± 3.23 0.443 With POD 1day 14 (12.5%) 7 (5.83%) 0.049 1 day 16.64 ± 4.90 16.70 ± 5.01 0.913 16.01 ±4.01 0.935 new-onset POD 1week 14 (12.5%) 7 (5.83%) 0.049 1 week 10.30 ± 3.00 11.30 ± 3.22 0.316 11.30 ± 3.22 0.316 floaters POD 1month 10 (8.93%) 10 (8.33%) 0.442 †Chi-square test P < 0.05 POD 8 (7.14%) 10 (8.33%) 0.271 Group 1: used dispersive ophthalmic viscosurgical devices (OVDs) and did not 2months remove them before hydrodissection. Group 2: used dispersive OVDs and removed ≥10 new-onset floaters 6 (5.35%) 1 (0.08%) 0.125 some dispersive OVDs before hydrodissection. Group 3: used cohesive OVD POD: during entire follow-up postoperative day †Mann Whitney U- test P < 0.05 Group 1 : used dispersive OVDs and did not remove dispersive OVDs before hydrodissection. Group 2 : used dispersive OVDs and removed some dispersive OVDs before hydrodissection. Group 3 : used cohesive OVDs. POD : postoperative day.

Figure 1. Percentage of patients with new-onset floater symptom during follow-up after cataract surgery in all study groups. The number of patients with postoperative floater symptom was significantly higher in Group 1 compared to other groups at 1 day and 1 week postoperatively. However, this difference was not significant after 1 month. (†Mann Whitney U- test < 0.05; Group 1: used dispersive ophthalmic viscosurgical devices (OVDs) and did not remove dispersive OVDs before hydrodissection. Group 2: used dispersive OVDs and removed some dispersive OVDs before hydrodissection. Group 3: used cohesive OVDs

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remove them before hydrodissection. Because of these Discussion properties, cohesive OVDs are better than dispersive A few months after we switched from cohesive OVDs for avoiding IOP spikes, but less effective for to adhesive OVDs, which was newly added to our coating and protecting the intraocular tissue. Ease of clinic, during cataract surgery, we observed that more surgery, protection of the endothelium, and patients complained of floaters after cataract surgery. avoidance of an IOP spike are all factors that need to Because the cataract surgeries were uneventful and be considered while selecting an OVD; however, nothing changed but newly added OVDs, we considering one factor might negatively affect the suspected new OVDs for these symptoms. Previous others. While using dispersive OVDs, it should reports demonstrated that OVDs with higher always be kept in mind that careless maneuvers may molecular weight or sodium hyaluronate lead to rupture of the PC-AHM barrier. Because concentration might induce increased IOP and this unlike cohesive OVDs, it is difficult for dispersive changes in IOP stressed on PC-AMH barrier and OVDs to spontaneously pass through the corneal could disrupt it [10,11]. We presumed that the IOP incision site during hydrodissection, it is necessary to spike during surgery with the new OVDs was avoid sealing the wound during hydrodissection. responsible for these symptoms, so we attempted to In the current study, we used the side port for remove some OVDs during hydrodissection, since hydrodissection and the corneal incision was sealed this surgical steps is the point at which the IOP is the when the IOP surged. If hydrodissection is performed highest. Since we checked postoperative floater through the main corneal wound, it could help avoid symptoms routinely, we have compared the wound sealing, though not effectively. symptoms of floaters before and after the change of We compared floater symptoms between OVDs. PC-AHM barrier is thought to act as a different OVDs after cataract surgery because we mechanical barrier separating the physical and assumed that because of its dispersive character, functional anterior portion of the eye from the Discovisc might lead to a higher IOP spike than that posterior portion [10]. This barrier is well-maintained caused by Microvisc, resulting in an AMH tear, which during normal phacoemulsification and aspiration is the direct path between the anterior segment and operations; the anterior chamber material does not the vitreous. Through this passage, tiny lens cortical flow into the vitreous cavity. However, formation of materials or OVDs can spill over, resulting in floater an AHM tear offers a direct path from the anterior symptoms, especially those with a score of 4. portion of the eye to the vitreous cavity. In our study, Group 1 patients showed more Hydrodissection can be considered to be the floater symptoms than those in Group 2 and Group 3 most probable causative factor for AHM tear because at 1 day and 1 week after the surgery. More eyes had a the IOP becomes highest at this stage during score 4 in Group 1 than in Group 2 or 3 [6 eyes (5.13%) phacoemulsification surgery. The AHM adheres vs 0 or 1(0.08%)], though the difference was not firmly to the posterior lens capsule by means of the significant because of the small number of patients. hyaloidocapsular Ligament of Weiger and a tear is These two results support our assumption. frequently seen near the ligament [12,13]. In the Postoperative new-onset vitreous floaters have a presence of the injected viscoelastic materials, tendency to disappear within a few weeks; there was hydrodissection may place great stress on the Weiger no significant difference between the three groups at 1 ligament, causing a tear in the AHM. Viscoelastics month after surgery. I assume that, unlike floaters normally play important roles in maintaining a experienced prior to surgery, the postoperative surgical space in which CCC can be performed and floaters consisted of small lens particles or OVDs, also in protecting the corneal endothelium. Recently which might be absorbed within weeks, and therefore different properties of viscoelastics have been utilized the floater symptoms may be improve. Even though for application in various situations, as the magnitude the floater symptoms might resolve in a month, the of increase in the IOP during hydrodissection varies sequlae such as AHM tear or zonular damage remain widely depending on the type of viscoelastics used for a long time and can result in delayed zonular [14-16]. Dispersive OVDs have the ability to coat; they dehiscence, subluxation or dislocation of the lens work well to keep the corneal endothelium protected more than 10 years later. during phacoemulsification. Meanwhile, cohesive Dispersive OVDs are not easily removed in the OVDs are useful in creating and maintaining space in presence of high IOP, which can be useful in some the anterior chamber and relatively easy to remove as circumstances, such as when a shallow anterior a bolus. In the current study, because cohesive OVDs chamber is present due to high posterior pressure. In were spontaneously removed during the these cases, cohesive OVDs will easily become hydrodissection step, we did not have to deliberately displaced through the wound site, therefore making it

http://www.medsci.org Int. J. Med. Sci. 2018, Vol. 15 227 difficult to maintain the anterior chamber during 8. Khng C, Packer M, Fine IH , et al. Intraocular pressure during phacoemulsification. J Cataract Refract Surg. 2006; 32(2): 301-8. phacoemulsification. Since dispersive OVDs can not 9. Oshika T, Okamoto F, Kaji Y, et al. Retention and removal of a new viscous dispersive ophthalmic viscosurgical device during cataract surgery in animal only maintain anterior chamber in high IOP, but also eyes. Br J Ophthalmol. 2006; 90(4): 485-7. protect corneal endothelium, they would be a better 10. Kawasaki S, Suzuki T, Yamaguchi M, et al. Disruption of the posterior chamber – anterior hyaloid membrane during phacoemulsification and choice in these challenging cases. aspiration as revealed by contrast-enhanced magnative resonance. Arch The retrospective nature of the study and the Ophthalmol. 2009; 127(4): 465-70. 11. Kawasaki S, Tasaka Y, Suzuki T, et al. Influence of Elevated Intraocular small number of subjects were the limitations of this Pressure on the Posterior Chamber-Anterior Hyaloid Membrane Barrier study; however, we could not enroll more subjects During Cataract Operations. Arch Ophthalmol . 2011; 129(6): 751-7. 12. Hogan MJ, Alvarado JA, Weddel JE. Histology of the Human Eye. because of ethical constraints. We did not perform Philadelphia: WB Saunders Company; 1974: 607-37. cataract surgery in Group 1 fashion since we noticed 13. Bron AJ, Tripathi RC, Tripathy BJ. Wolff’s Anatomy of the Eye and Orbit, 8th ed. London: Chapman & Hall; 1997: 443-53. that patients in Group 1 complained of more floater 14. Modi SS, Davison JA, Walters T. Safety, efficacy and intraoperative symptoms than the patients in other groups. The characteristics of Discovisc and healon ophthalmic viscosurgical devices for cataract surgery. Clin Ophthalmol. 2011; 5: 1381-9. subjectivity in quantifying floater symptoms is 15. Neumayer T, Prinz A, Findl O. Effect of a new cohesive ophthalmic another limitation; because there is no objective viscosurgical device on corneal protection and intraocular pressure in small incision cataract surgery. J Cataract Refract Surg. 2008; 34(8): 1362-6. method to evaluate floater symptoms, we had to rely 16. Koch DD, Liu JF, Glasser DB, et al. A comparison of corneal endothelial changes after use of Healon or Viscoat during phacoemulsification. Am J on the patients’ subjective views. To reduce such a Ophthalmol. 1983; 115(2): 188-201. subjective bias, we focused on severe floater symptoms only. Notwithstanding these limitations, to our best knowledge, this is the first study about postoperative floater symptoms, linking the characteristics of viscoelastic materials and IOP. This report contributes to our understanding of early onset postoperative floater symptom, to help reducing the occurrence of symptoms. Comparison of delayed complications such as lens subluxation or dislocation with this cohort will be a meaningful study in the future. In conclusion, without release of the OVDs from the anterior chamber before hydrodissection, the eye has an increased risk of PC-AHM rupture during hydrodissection, especially with dispersive OVDs. The breakdown of the PC-AHM barrier potentially leads to numerous floaters. Thus, surgeons should consider releasing some OVDs during hydrodissection with dispersive viscoelastics and attempt to avoid IOP surge during surgery. Competing Interests All authors (Jinsoo Kim, Hak Jun Lee, In Won Park, Soon Il Kwon) declare that there are no conflicts of interest regarding the publication of this paper. The authors are responsible for the content and writing of the paper. References 1. Davidson JA. Ultrasonic power reduction during phacoemulsification using adjunctive NeoSoniX technology. J Cataract Refract Surg. 2005; 31(5): 1015-9. 2. Soscoa W, Howard JG, Olson RJ. Microphacoemulsification with WhiteStar: a wound-temperature study. J Cataract Refract Surg. 2002; 28(6): 1044-6. 3. Hollands H, Johnson D, Brox AC, et al. Acute-Onset Floaters and Flashes Is This Patient at Risk for Retinal Detachment? JAMA. 2009; 302(20): 2243-9. 4. Hogan MJ. The vitreous,Its structure in relation to the ciliary body and retina. Invest Ophthalmol. 1963; 2: 418-45. 5. Schweitzer KD, Eneh AA, Hurst J, et al. Predicting retinal tears in posterior vitreous detachment. Can J Ophthalmol. 2011; 46(6): 481-5. 6. Thompson JT, Glaser BM. Role of lensectomy and posterior capsule in movement of tracer from vitreous to aqueous. Arch Ophthalmol. 1985; 103(3): 420-1. 7. Faust KJ. Hydrodissection of soft nuclei. J Arn Intraocul Implant Soc. 1984; 10(1): 75-7.

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